Allen was born in Latonia, Kentucky. In 1931, with Drew Pearson, he anonymously co-authored Washington Merry-Go-Round (New York, H. Liveright)[1] and More Merry-Go-Round and later wrote the daily column of the same title.

He was a veteran of World War I and served on General Patton's staff in World War II. According to John Earl Haynes, Harvey Klehr and Alexander Vassiliev in their 2009 book Spies: The Rise and Fall of the KGB in America,[2][3] Robert Allen was instrumental in co-opting the recognition of the Soviet Union by the Roosevelt Administration, opening the way for the Soviet Union to be that allied force during World War II.[4]

"In 1933, Allen was a fully recruited and undoubtedly witting Soviet agent. Under the assigned cover name of “George Parker,” he covertly exchanged privileged information for money. He provided the Soviets with intelligence about Japanese military fortifications; news about potential appointments in the incoming Roosevelt administration; and information about the US government’s plans for diplomatic recognition of the Soviet Union."

In the early forties he co-wrote the newspaper strip Hap Hopper with Drew Pearson. The strip was drawn by Jack Sparling.[5]

In 1947, he edited the book, Our Fair City,[6] an expose of corrupt conditions in American municipalities. He also wrote Lucky Forward: The History of Patton's Third Army. Papers concerning his military career reside in the George S. Patton Museum at Fort Knox, Kentucky.

Allen was a CIA wiretap subject, according to documents released by the agency in 2007.

"Under pressure from Attorney General Robert F. Kennedy" in 1962, CIA director John McCone "agreed to tap the telephones of columnists Robert S. Allen and Paul Scott in an effort to identify their sources for classified information which was appearing in their columns," says a memo[7] a decade later to the agency's director."[8]

He died in Georgetown, Washington, D.C. from a self-inflicted gunshot wound. Allen, who had cancer, had ended his journalism career when his illness made it impossible for him to work.